A few years ago, it was common to use large hoods and provide a suction so that gases arising in an area beneath them would be drawn to them and exhausted through appropriate ducting. Alternatively, the room in which fumes from welding or some other air polluting operation originated was well ventilated. These approaches to the problem required the movement of large volumes of air.
Source removal of fumes is much more efficient. The present invention is directed to a source exhauster. In this regard, it is noted that other source exhausters are known. U.S. Pat. No. 3,818,817 shows an adjustable assembly having lever arms about which there is draped flexible tubing which extends from a suction casing attached to a fan. The problem with this system is that the structural assembly is located within the fluid communication tubing and, consequently, makes fluid flow difficult and requires substantial suction.
A system is also known which provides adjustable supporting mechanism on the outside of flexible tubing. Such system eliminates the fluid flow problem, but is rather unsightly and requires adequate space in which to locate the external superstructure.
A further fume extractor is shown in design U.S. Pat. No. 285,832. Apparently, each arm segment is rigid and attached to the next at a hollow axle portion. Although there is not internal structure, fumes must make two right angle turns at each axle portion. Consequently, fluid flow is still subject to substantial resistance.
The present invention eliminates external structure and locates internal structure in regions of relatively low flow.